35 lines
1,000 B
Text
35 lines
1,000 B
Text
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# Errors
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RETRO does only minimal error checking.
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## Non-Fatal
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A non-fatal error will be reported on *word not found* during
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interactive or compile time. Note that this only applies to
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calls: if you try to get a pointer to an undefined word, the
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returned pointer will be zero.
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## Fatal
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A number of conditions are known to cause fatal errors. The
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main ones are stack overflow, stack underflow, and division
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by zero.
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On these, RETRO will generally exit. For stack depth issues,
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the VM will attempt to display an error prior to exiting.
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In some cases, the VM may get stuck in an endless loop. If this
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occurs, try using CTRL+C to kill the process, or kill it using
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whatever means your host system provides.
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## Rationale
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Error checks are useful, but slow - especially on a minimal
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system like RETRO. The overhead of doing depth or other checks
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adds up quickly.
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As an example, adding a depth check to `drop` increases the
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time to use it 250,000 times in a loop from 0.16 seconds to
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1.69 seconds.
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